Vertical surface vapor condensers

ABSTRACT

Improvements in vertical tube or column type surface vapor condensers are disclosed comprising means positioned within the tubes engaging the inner tube walls for guiding condensate away from that primary condensing surface to remove condensate from the condensing surfaces to improve heat transfer. Three types of guide means are disclosed, a tree-like structure having a central trunk and a plurality of up-reaching and spreading wire branches which contact the tube interior wall and remove condensate capillary action as well as gravity; a second tree-like unit having U-shaped double branch contacters extending for a length along the tube wall for increased capillary action and a funnel type that includes a plurality of opening upward split-walled funnels which are affixed at spaced intervals along a central rod and have their outer edges engaging the tube interior walls.

ilnited States Patent 1 Newton VERTICAL SURFACE VAPOR CONDENSERS I [75] Inventor: Alwin B. Newton, York, Pa.

[73] Assignee: Borg-Warner Corporation, Chicago,

Ill.

22 Filed: ot.4,1972

211 Appl. No.: 295,086

Related US. Application Data [63] Continuation-in-part of Ser. No. 71,539, Sept. 11

1970, abandoned.

[52] US. Cl.. 165/111, 165/174, 138/38 [51] int. Cl. F281) 9/08 [58] Field of Search 165/110, 111, 174, 179; v 138/38 [56] References Cited UNITED STATES PATENTS 2,310,970 2/1943 Limpert 165/179 X 2,359,288 10/1944 Brinen 165/174 X 2,503,595 4/1950 Preston.... 165/179 X 2,970,669 2/1961 Bergson... 165/111 X 3,050,957 8/1962 Robbie 62/303 X 3,273,599 9/1966 Heeren 138/38 3,468,345 9/1969 Tam et al. 138/38 3,508,608 4/1970 Roe 165/111 X FOREIGN PATENTS OR APPLICATIONS l/1959 France 165/177 [451 Sept. 24, 1974 Primary ExaminerAlbert W. Davis, Jr. Attorney, Agent, or FirmThomas B. Hunter 57 ABSTRACT Improvements in vertical tube or column type surface vapor condensers are disclosed comprising means positioned within the tubes engaging the inner tube walls for guiding condensate away from that primary condensing surface to remove condensate from the condensing surfaces to improve heat transfer. Three types of guide means are disclosed, a tree-like structure .having a central trunk and a plurality of up-reaching and spreading wire branches which contact the tube interior wall and remove condensate capillary action as well as gravity; a second tree-like unit having U- shaped double branch contacters extending for a length along the tube wall for increased capillary action and a funnel type that includes a plurality of opening upward split-walled funnels which are affixed at spaced intervals along a central rod and have their outer edges engaging the tube interior walls.

1 Claim, 7 Drawing Figures mmwsmmw 3.837. 396.

FIG.1 SOIGJ k 'FIG. 3 a ma 1 VERTICAL SURFACE VAPOR CONDENSERS CROSS-REFERENCE TO RELATED APPLICATION FIELD OF THE INVENTION This invention is directed toward an improvement in vapor condensers of the surface type, such as those used with refrigeration equipment. It is especially concerned with improvements in generally vertical column or tube condensers.

BACKGROUND OF THE INVENTION Condensers having generally vertical condensing walls one side of which is cooled, as by directing a coolant such as air across it and the other side of which serves as the primary condensing surface on which the condensate is formed and flows by gravity to a low point for removal are well known in the art. For a general discussion of condensers, including this type, reference may be had to Volume 3 of the McGraw-Hill Encyclopedia of Science and Technology pp. 377 to 382, especially at p. 382.

It is also well known to use interior members in tube evaporators such as those described in U.S. Pat. Nos. 3,273,630, 2,480,706, 837,582 or in heat exchangers such as those described in U.S. Pat. Nos. 3,068,905, 2,905,447, 2,310,970 and 2,068,955. However, the problems of condenser construction and operation are quite different from those of evaporators and other heat exchangers.

The guide means are preferably constructed of a thermally conducting material such as aluminum so as to also add to the cooling surface. However this is not necessary and even plastic guide means may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with the further advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIG. 1 is a simplified diagrammatic representation of refrigeration system including an air cooled vertical tube condenser, incorporating the present invention;

FIG. 2 is a longitudinal sectional view ofa portion of one of the vertical condenser tubes of the condenser of FIG. 1, in which, in accordance with the present invention, condensate guide means are provided;

FIG. 3 is a longitudinal sectional view of a portion of a vertical condenser tube, such as those employed in the condenser of FIG. 1, in which a second embodiment of the invention is employed;

FIG. 4 is a transverse sectional view of the tube of FIG. 3, as seen from the line 4-4 thereof;

FIG. 5 is a longitudinal sectional view of a portion of a vertical condenser tube, such as those employed in the condenser of FIG. 1, in which yet another embodiment of the invention is incorporated;

FIG. 6 is a transverse sectional view of the tube of FIG. 5 as seen from the line 6-6 thereof; and

FIG. 7 is a longitudinal sectional view of a portion of a condenser tube constructed in accordance with the present invention.

DETAILED DESCRIPTION Referring now to FIG. 1, there is depicted a refrigeration system generally designated 8. The system 8 includes a compressor 9, which discharges hot compressed refrigerant gases into a vapor condenser generally designated 10. The condenser 10 is of the vertical tube surface condenser type and includes a plurality of generally vertical tubes 12 which, in an air cooled construction usually include fins 14 or other heat exchange surface. Air or other coolant is directed between the fins 14 and by the tubes 12. Gas or vapor enters the condenser tubes at a top inlet or header 20 and liquid condensate is removed from a bottom sink or outlet 22. From that outlet 22 the now liquid refrigerant travels to an expansion valve 23 and from there to an evaporator 25 where the refrigerant vaporizes, taking up heat. Vapor is drawn from the evaporator 25 to the compressor 9 from which, after compression, it is continuously fed to the condenser 10.

In accordance with the present invention the tubes 12 of the condenser 10 are provided, as may best be seen in FIG. 2, with means (generally designated 30) for guiding condensate from the interior primary condensing surface 128. As used herein the term primary condensing surface means a vapor condensing surface segment such as the interior tube surface of a structure or wall, such as the curving wall of the tube 12, which has its opposite side or surface in substantial contact with coolant, either directly or with the aid of external fins, such as the fins 14, and does not encompass incidental surfaces which, like internal fins, for example, might aid in condensation.

The guide means 30, in this embodiment, comprises a tree-like member having a central rod or trunk 32 and a plurality of upwardly and outwardly extending spires or branches 34 which extend on all sides of the trunk 32 in a more or less random array. The spires 34 are preferably thin wire segments which are twisted together in the main trunk wire.

In operation, the spires 34 serve to guide or pick off, from their points contacting the surface 128, the condensate primarily by capillary action, which condensate then runs down them to the trunk 32. This condensate then is guided down the trunk 32 toward the vicinity of the outlet 22 without again flowing onto the condensing surface 12S.

The tree-like guide means 30 is preferably made with spires or branches 34 of a length greater than the radius of the tube 12 in which it is to be employed. The branches 34 are preferably initially constructed so as to be roughly perpendicular to the trunk 32 and assume their depicted orientation during the assembly of the tube when the means 30 is inserted from the upper end. This method of manufacture has the advantage of providing a secure mounting of the means 30, within the tube as well as sure contact between the outer end of the branches 34 and the surface 128.

Referring now to FIGS. 3 and 4 a second embodiment of the invention is illustrated. In this embodiment, guide means 30 are used, each comprising a generally centrally located trunk member or rod 32' to which generally U-shaped branch units 34' are affixed at spaced intervals.

The U-shaped units 34 are formed with upright lengths 35 which extend for a considerable vertical distance along the primary condensing surface 128 to gather, by capillary action, condensate fluid between the sides of the lengths 35 and the adjacent portions of the surface 125. This fluid is moved downward by gravity until it runs along the bottom of arcuant portions 36 curving toward the rod 32. Before the portion 36 reaches the rod 32', it joins with depending extensions 38 which lie at the lowest point on the U-shaped branch units 34'. These extensions 38 serve as departure points for the fluid to drip down to the bottom of the tube 12.

The branch units 34 are preferably positioned at randomly located planes about the rod 32. Theslightly off-center position of the U-shaped branch units 34 and their random orientation provide drop paths that inherently will intercept few, if any, of the lower U- shaped branch units 34'. The units 34 are also preferably of a resilient material and so formed as to bear against the surface 128 to assure good contact therewith as well as to secure the means 30' within the tube 12.

Referring now to FIGS. 5 and 6 there is depicted a third guide means 30" for insertion into the vertical condenser tubes 12. This means 30" also comprises a generally central trunk or rod 32". However instead of the thin branch members 34 or 34 of the previous embodiments a branching out funnel unit 34" is provided to guide the fluid from the surface 125 toward the central zone of the tube 12.

These funnels 34" are preferably made of a thin metal but may also be made ofa relatively flexible plastic that can withstand this environment of use. The normal diameter of the units 34 is slightly greater than the interior diameter of the tube 12. A radial slit 40 provided to allow the unit to compress while being inserted into the tube 12. This resiliently holds the guide means 30" in place and urges the outer edge 42 of the funnel tightly against the surface 128.

The funnel 34" slopes downwardly from the edge 4b at a sharp incline in a rim section 44. The area of contact between the surface 128 and the rim section 44 is preferably kept quite small. To achieve this and to provide continuity of the flow surface from the tube surface to the upper surface of the funnels 34" the upper edge of the section preferably tapers down to a knife-like edge. From the bottom of the rim section the funnel unit 34 extends at a smaller incline 46 to a circular opening and depending rim 48 to which the rod 32" is affixed (as by spot welding).

The funnels 34" are preferably affixed to the rod 32 so that their slits 40 do not lie over each other.

In operation, condensate forming on the surface 128 between the funnels 34" flows by gravity to the rim edge 42. From there it cascades down the rim 44, the section 46 to either the depending hub rim 48 or to the rod 32". That part that reaches the rod 32" flows along it until it reaches the bottom of the rod 32". That part that flows over the rim 48 drops down to the next funnel and eventually reaches the bottom of the guide means 30".

While it may be possible in the embodiment of FIGS. 5 and 6 to eliminate the rod 32" that rod is preferred so as to fix the spacing between funnels 34", to provide a rigid structure, to aid in flow direction and to aid in assembly of the guide means into the tube 12. The funnel spacing is such as to provide condensation chambers each of a vertical height so that no appreciable film thickness developes to impede heat transfer.

Referring to FIG. 7 there is illustrated a further condenser tube constructed in accordance with the present invention wherein the relatively high vapor velocity zone, the upper section of the tube 12, is equipped with guide means 30 of the type described above in conjunction with FIG. 2, while the lower gas velocity zone, the lower section of the tube 12, is equipped with the means 30" of the type described in conjunction with FIGS. 5 and 6. With the construction the vapor initially entering the tube meets with little resistance to its flow as a result of the guide means 30. Some of this vapor is removed as condensate in the upper part of the tube 12 resulting in a lower velocity of vapor flow in the lower portion of the tube 12 where the higher flow resisting guide means 30" is provided.

As should now be apparent an improvement in vertical surface vapor condensers has been described which provides for increased capacity of condensation per unit area of primary condensing surface. This more effective condensation allows for more efficient operation and/or decreased material utilization and size and produces other advantageous results.

While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A vapor condenser comprising: a plurality of substantially vertical tubes through which vapor to be condensed is caused to flow, each said tube including an inner condensing surface and an outer surface adapted to be cooled by a fluid medium; and condensate guide means located within said tubes adapted to remove condensed vapor from said condensing surface to improve the heat transfer of said condenser, said guide means including a central rod extending lengthwise of said tube, said rod being spaced from and out of contact with said condensing surface, and a plurality of flexible, upwardly and outwardly extending, wire-like branches each having one end connected to said rod and the opposite end in point contact with said condensing surface, said branches extending from all sides of said rod in random array whereby condensate is picked off the condensing surface by capillary action and guided downwardly along said branches toward said rod. 

1. A vapor condenser comprising: a plurality of substantially vertical tubes through which vapor to be condensed is caused to flow, each said tube including an inner condensing surface and an outer surface adapted to be cooled by a fluid medium; and condensate guide means located within said tubes adapted to remove condensed vapor from said condensing surface to improve the heat transfer of said condenser, said guide means including a central rod extending lengthwise of said tube, said rod being spaced from and out of contact with said condensing surface, and a plurality of flexible, upwardly and outwardly extending, wirelike branches each having one end connected to said rod and the opposite end in point contact with said condensing surface, said branches extending from all sides of said rod in random array whereby condensate is picked off the condensing surface by capillary action and guided downwardly along said branches toward said rod. 